Not sure if it helps, but here is it: root@lab1:/mnt/vol1# btrfs filesystem df /mnt/vol1/ Data, RAID10: total=116.00GiB, used=110.03GiB Data, single: total=8.00MiB, used=0.00 System, RAID1: total=8.00MiB, used=16.00KiB System, single: total=4.00MiB, used=0.00 Metadata, RAID1: total=2.00GiB, used=563.72MiB Metadata, single: total=8.00MiB, used=0.00 unknown, single: total=192.00MiB, used=0.00
On Mon, Feb 9, 2015 at 8:56 PM, Kai Krakow <hurikha...@gmail.com> wrote: > P. Remek <p.rem...@googlemail.com> schrieb: > >> Hello, >> >> I am benchmarking Btrfs and when benchmarking random writes with fio >> utility, I noticed following two things: >> >> 1) On first run when target file doesn't exist yet, perfromance is >> about 8000 IOPs. On second, and every other run, performance goes up >> to 70000 IOPs. Its massive difference. The target file is the one >> created during the first run. >> >> 2) There are windows during the test where IOPs drop to 0 and stay 0 >> about 10 seconds and then it goes back again, and after couple of >> seconds again to 0. This is reproducible 100% times. >> >> Can somobody shred some light on what's happening? > > I'm not an expert or dev but it's probably due to btrfs doing some > housekeeping under the hood. Could you check the output of "btrfs filesystem > usage /mountpoint" while running the test? I'd guess there's some pressure > on the global reserve during those times. > >> Command: fio --randrepeat=1 --ioengine=libaio --direct=1 >> --gtod_reduce=1 --name=test9 --filename=test9 --bs=4k --iodepth=256 >> --size=10G --numjobs=1 --readwrite=randwrite >> >> Environment: >> CPU: dual socket: E5-2630 v2 >> RAM: 32 GB ram >> OS: Ubuntu server 14.10 >> Kernel: 3.19.0-031900rc2-generic >> btrfs tools: Btrfs v3.14.1 >> 2x LSI 9300 HBAs - SAS3 12/Gbs >> 8x SSD Ultrastar SSD1600MM 400GB SAS3 12/Gbs >> >> Regards, >> Premek > > -- > Replies to list only preferred. > > -- > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
